Sablefish, also known as black cod, is a tasty, buttery fish valued on the seafood market. While sustainably managed, the wild population is lower than in the past, and fishermen have been harvesting fewer of them.
Researchers at NOAA Fisheries Northwest Fisheries Science Center are experimenting with raising farmed sablefish in hopes of creating a viable U.S. commercial aquaculture industry. However, like many marine finfish species, sablefish can be challenging to produce and grow on a commercial scale because of the high cost and challenges associated with reproduction, larval rearing, and grow-out to harvest size.
Improving Rearing Practices, But Challenges Remain
For over a decade, science center researchers have been developing technologies for culturing sablefish from eggs to adults and better understanding their biology and life cycle.
Raising farmed sablefish begins with wild broodstock. Researchers collect and fertilize the eggs in vitro and then transfer them to environmentally-controlled incubators. After hatching, they are reared in tanks through the larval and juvenile stages and then moved to net pens at the Manchester Research Station in Port Orchard, Washington.
Through these efforts, our researchers and their collaborators have drastically improved rearing practices to reduce costs and improve production. For example, they've optimized tank design, elevated temperatures to shorten the larval rearing phase. They also substituted an inexpensive alternative (clay) in place of algae for producing opacity in rearing water during the larval stage.
Also, center researchers have developed non-GMO techniques to produce all-female stocks of sablefish for aquaculture. The culture of all-male or all-female populations is known as "monosex" culture. These monosex female sablefish stocks have significantly higher growth rates than stocks that include slower-growing males.
However, challenges remain in making sablefish aquaculture a profitable commercial industry. Researchers have overcome many technical challenges, but there remain significant bureaucratic and social constraints. For example, major hurdles include securing permits to grow fish in net pens and identifying groups willing to invest in the infrastructure necessary to support commercial-scale production.
Transferring the Latest Technology to the Jamestown S'Klallam Tribe
Since 2014, the science center, the Jamestown S'Klallam Tribe, and most recently, the University of Washington (with support from Sea Grant) have been experimenting with net pen grow-out of sablefish. This partnership aims to develop and transfer knowledge and technology to the tribe in hopes of initiating commercial-scale operations in the United States.
In a recent project involving both the Jamestown S'Klallam Tribe and Cooke Aquaculture Inc., researchers stocked monosex female sablefish fingerlings in the Manchester Research Station's net pens. Staff from the science center and the Jamestown S'Klallam Tribe grew the fingerlings to commercial size over approximately 18 months.
Project researchers assessed sablefish growth and health. They also tracked environmental parameters such as temperature and oxygen levels in the pens. At the same time, collaborators from the University of Washington analyzed the effects of the net pen grow-out on sediments beneath and surrounding the pens to test for environmental impacts.
These were among the first cultured sablefish harvested in the United States, and the markets for this product are still developing. The partnership continues to tackle the technical aspects and lay the groundwork for net pen grow-out of sablefish by Native American tribes and other interested parties along the U.S. West Coast.